Abstract
Abstract. Nearly two years of 2-min resolution data and 7- to 21-s resolution data from the CUTLASS Finland HF radar have undergone Fourier analysis in order to study statistically the occurrence rates and repetition frequencies of pulsed ionospheric flows in the noon-sector high-latitude ionosphere. Pulsed ionospheric flow bursts are believed to be the ionospheric footprint of newly reconnected geomagnetic field lines, which occur during episodes of magnetic flux transfer to the terrestrial magnetosphere - flux transfer events or FTEs. The distribution of pulsed ionospheric flows were found to be well grouped in the radar field of view, and to be in the vicinity of the radar signature of the cusp footprint. Two thirds of the pulsed ionospheric flow intervals included in the statistical study occurred when the interplanetary magnetic field had a southward component, supporting the hypothesis that pulsed ionospheric flows are a reconnection-related phenomenon. The occurrence rate of the pulsed ionospheric flow fluctuation period was independent of the radar scan mode. The statistical results obtained from the radar data are compared to occurrence rates and repetition frequencies of FTEs derived from spacecraft data near the magnetopause reconnection region, and to ground-based optical measurements of poleward moving auroral forms. The distributions obtained by the various instruments in different regions of the magnetosphere were remarkably similar. The radar, therefore, appears to give an unbiased sample of magnetopause activity in its routine observations of the cusp footprint.Key words: Magnetospheric physics (magnetosphere-ionosphere interactions; plasma convection; solar wind-magnetosphere interactions)
Highlights
Magnetic reconnection is a fundamental process in the dynamics of the magnetosphere
The ®rst published observations consistent with episodic bursts of reconnection at the magnetopause were made at the magnetopause on board the Heos 2 satellite by Haerendel et al (1978), who discussed a number of potential physical mechanisms of mass and momentum transfer from the solar wind to the magnetosphere
Simultaneous spacecraft and ground-based observations of the reconnection region and its footprint, which are dicult to achieve, have since shown that the ionosphere does respond to FTEs and that the response is detectable as periodic anti-sunward ionospheric convectiveow bursts (Elphic et al, 1990; Moen et al, 1995; Yeoman et al, 1997; Neudegg et al, 1999)
Summary
Magnetic reconnection is a fundamental process in the dynamics of the magnetosphere. The merging of the interplanetary magnetic ®eld (IMF) and the geomagnetic ®eld on the dayside provides the primary mechanism for energy input to the cyclic system (Dungey, 1961). Ground-based evidence of magnetopause reconnection followed when Goertz et al (1985) used the STARE radar (Greenwald et al, 1978) to detect antisunwardow poleward of the convection reversal boundary with an occasional signi®cant north-south component, as well as sporadicow across the convection reversal boundary with scale sizes of 50 to 300 km and repetition rates of the order of minutes. These types ofows are consistent with the predicted response of the ionosphere to reconnection events at the magnetopause. Simultaneous spacecraft and ground-based observations of the reconnection region and its footprint, which are dicult to achieve, have since shown that the ionosphere does respond to FTEs and that the response is detectable as periodic anti-sunward ionospheric convectiveow bursts (Elphic et al, 1990; Moen et al, 1995; Yeoman et al, 1997; Neudegg et al, 1999)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
